Sunday, April 14, 2013

It's alive! How mad science in the workshop created a Franken-Radish

My first Xtracycle was fun but flawed. Mostly I didn't like the upright riding position and the fact that the donor frame was a mountain bike frame that was a bit on the small side for my 6' 1" stature. That frame was great as a mountain bike for technical singletrack, but terrible as the donor bike for an Xtracycle. My first attempt at building a cargo bike was chronicled here

The original bike on one of the early test rides.

I tried to salvage the original build by changing the handlebars from a mountain bike riser bar to a "butterfly" or "trekking" bar, to see if that would help with the riding position. Before I could even take the bike out for a test ride with the new trekking bars, the mock up in the workshop made it clear that I still wouldn't be able to achieve a riding position that would be comfortable for lengthy rides hauling lots of cargo. So, it was back to the drawing board.

I began canvassing the internet looking for both used and new mountain bike frames that might fit me better and thus allow me to make a more comfortable Xtracycle. I few short weeks of looking and it was patently obvious that most mountain bike frames are now made to accept suspension, (mostly useless for cargo bikes), or more likely were not available in a size that would fit me or were lacking in the appropriate geometry. One of my searches turned up a reference to another Xtracycle builder who replaced a broken mountain bike frame with the front half of an Xtracycle Radish frame.

Intrigued by this option, I went back the Xtracycle website and took a long hard look at the current version of the their ready-made longtail, the Radish.

I liked the concept of the step-through frame, which has become somewhat of a design standard in purpose-built cargo bikes as reflected by other companies offerings such as the Yuba Mundo, or Trek Transport. I wasn't sold yet though. I kept looking for what I thought would make the most suitable frame.

I briefly considered purchasing a bare Surly Long Haul Trucker frame, but the cheapest purchase price I could find was $400. That would've put the cargo bike build WAY over budget and ultimately I simply couldn't justify it, even though I had photographic and blog evidence that some other folks had built Xtracycles based on Long Haul Truckers and that it had worked well for them as you can see here:

and here:

Remembering the post regarding Radish frames, I decided to call the folks out in California at Xtracycle HQ. I spoke with two really helpful guys, Robert and Nate. I told them what I wanted to do, replace my current mountain bike frame, and could I buy just the front half of a Radish, seeing as how I already had the FreeRadical cargo bit. Robert went to check the shop and returned to the phone to tell me that yes, in fact they happened to have the front half of a Radish frame there in the shop. For $250 the Radish frame could be mine. A credit card number was given and the Radish frame along with a couple wide loaders were added onto the order as well.

My dealings with Robert and Nate were not over though. I called back a few days later and spoke with Nate at length regarding some questions I had about the Radish frame. I wanted to know if the frame I was getting was the one with the step-through design or the earlier one without. It was in fact the step-through. Also, the Radish as it is currently sold, only comes with a single front chain ring. I wanted to add a triple chain ring to increase the gearing capacity. Nate gave me tubing dimensions to help in purchasing anything else I'd need to build out the bike, since what I was getting was merely a bare frame and fork with no installed components.

So, when my Radish arrived it was merely the frame and fork along with the special nut and bolt that attach the yoke of the FreeRadical to a welded plate sandwiched between the chainstays on the front part of the frame. The Radish is available in any color you want as long as it's a sort of creamy ivory color. Not being a fan of the cream color, and being too far over budget to consider powder coating the frame and FreeRadical, I elected to rattle-can the frame a matching silver color. I roughed up the frame and fork with synthetic steel wool so that the new paint would have something to adhere to. The paint I chose was a sparkly metallic silver color made by Dupli-Color intended for painting alloy wheels. The specific product is Dupli-Color High Performance Wheel Coating. I applied six coats over two weeks and followed it up with another six coats of clear coat, also applied over two weeks.

The frame isn't an exact match but it's not too obvious in person. The frame ended up being a bit more of a champagne silver color.

The completed "Franken-Radish" in all its glory. My choice of the "Franken" moniker will become readily apparent, as this is FAR from your typical Xtracycle Radish.

I gave the trekking bars a try again with the Radish frame, but they still weren't working out for me. Do those bars work for anyone? I've seen them on a lot of touring bikes, but every time I've tried them on a bike, they've given me a choice between a riding position that was too upright, too stretched out, or somewhere in between but with no access to the brakes. At this point I just decided to put drop bars on the bike and be done with it. Drop bars on Xtracycles are probably the least common choice for handlebars, but I'm determined to make it work. My choice was the Ritchey Biomax cyclocross handlebar. What makes this bar more comfortable are the shallow drops with ergonomic bend as well as a slight outward flare and 6 degree swept back tops. Ritchey apparently no longer makes the 26mm clamp version, instead selling only a 31.8mm version. As with my communter bike, I was able to find the best price on a 46cm width bar at

Since Xtracycles use V-brakes or disc brakes for maximum stopping power, I chose to stick with V-brakes. They're easily adjustable, and besides the Radish frame does not have a disc brake mount on the front fork, only on the FreeRadical. I used Cane Creek Drop-V levers coupled with Paul Components Cross Levers. I like having cross levers so that I can control my brakes without always having to ride with my hands on the brake hoods. Unfortunately, Paul Components is the only company making a cross lever that will work with either short pull brakes such as caliper and cantilevers or long pull brakes such as V-brakes and mechanical pull disc brakes. I say this is unfortunate because the Paul levers cost upwards of $90. This is about as niche as you can get when it comes to brakes though, so it's no surprise that a company like Tektro doesn't make a long pull interrupter lever. One minor complaint about the Paul levers - they require the use of a snap ring pliers to switch the pivot between short pull and long pull. I've no idea why they couldn't have used a simple nut and bolt arrangement. I had to spend another $20 for a pair of snap ring pliers just to change the pivots. At least now I have the pliers in case I ever need them in the future. Note the upper opening in the cross levers for the short pull option.

I used special Tektro 857 AL V-brakes with extra-long arms that allow for fender clearance. I'm a weirdo in that I like to run my right brake lever to the front brake, which is the exact opposite of how most bikes are made and built here in the United States. This coupled with the cross levers resulted in having to use the brake noodle with the sharper bend. Thankfully Tektro includes these sharper bend noodles along with the more standard 90 degree type. Note the cycle computer wires wrapped around the brake cable, helping to add to that Fraken-bike appearance.

I used Crank Brothers Candy 1 pedals, same as I use on my commuter bike. I love Crank Brothers pedals because they can be completely serviced and rebuilt, a rarity among clipless pedals. You can see the cadence sensor for my computer attached to the chain stay and crank arm. One of few concessions to aesthetics, I chose a white zip tie for the crank arm instead of traditional black.

Back on the FreeRadical end of things, you can see the use of the standard noodle for the rear brakes. Also, you can see my unicycle two-bolt seatpost clamps that were used as makeshift Watchamacollars
. They're not as pretty as the Xtracycle version, but they get the job done and they only cost about $28, so less than buying a single set of the regular ones. Still, I had to make my own shims and add in some O-rings to seal water out.

The Radish frame will accept tires up to 26x2.35 tires, although I tried mounting 26x2.35 Schwalbe Big Bens on my previous Xtracycle and found the clearance in FreeRadical was so tight that you wouldn't be able to run fenders. I decided to be more conservative and instead installed Schwalbe Marathon HS 420 tires in 26x2.0 size. The Marathon HS 420 has a 130kg load limit whereas the Big Apple, tire of choice for many cargo biking folks is only rated for 125kg in the same size. The minor tread should be good enough for crushed limestone trails as well as fire roads and light off roading.

Due to the much lower top tube geometry with the Radish frame, it was recommended that I buy at least a 400mm seatpost. I was able to go one better and I found the Gusset Lofty XXL seatpost which can be purchased in the ridiculously long length of 450mm with an awesome micro adjusting two bolt seat clamp. I topped it off with the same Brooks B17 saddle transferred over from the previous build. A Brooks B17 is the only kind of saddle I'll ever ride. Once you've drunk the Brooks Kool-Aid there's no going back to foam, plastic, and vinyl ass-hatchets.

Keeping the crud off of everything are SKS Chromoplastics fenders. If I had this to do over again, I'd buy the SKS Blumells which offer the same coverage but are slightly longer and not as glossy in appearance. Still, I really like SKS fenders and find them to have the most sturdy mounting hardware of any of the fender manufacturers I've looked at. I will be retrofitting an SKS rubber mudflap to the front fender though to increase the amount of coverage and thus cut down on spray getting on the lower bits of the bike frame. Shifting is still being accomplished with the Shimano Alivio rear derailleur which made its way over from the last cargo bike. The Avid Rollamajig is still in use as well, taking care of shortening that cable run going into the rear derailleur and insuring shifts will be crisp and precise.

The only "old" component to make it into this build are the wheels which will soon be replaced by new custom-built 36 hole wheels built around Sun Rhyno-lite rims, and this ancient, but little-used Suntour XC Pro mountain bike crankset. Peculiar cable routing issues meant my original Suntour front derailleur had to be replaced with this top-pull Shimano Alivio derailleur. Since there are no derailleur mounts or cable stops for such, I had to install a Problem Solvers Back Stop cable stop on the seat tube to allow me to run cable to the front derailleur.

I chose to run Shimano SL-BS50 8 speed bar end shifters for their practically bombproof reliability and because they can be switched to operate in full friction shifting mode if necessary. Installing these shifters meant I had to have some unorthodox cable routing, particularly because there are no downtube shifter bosses and no cable stops for a front derailleur. Complicating matters was the step-through top tube design. There is a slightly asymmetrical appearance to how the cables run off of the bar ends and you can see how the front derailleur cable must run along the top tube, held in place by Problem Solvers Clamp-On Cable Guides. The asymmetrical cable routing only slightly messes with my sense of aesthetics, but best of all helps contribute to the overall "Franken-bike," or in this case "Franken-Radish" appearance.

And another view of that "Franken-Radish" cable routing.

And so we come to end of this terrible tale of woe and intrigue. With 60 miles of saddle time since completion, I can say that I've hit upon, what is for me, a good balance of comfort and speed and I think this bike will still do well when finally loaded with more cargo than a couple packed panniers. Expect to read more trip reports as the Franken-Radish begins its cargo-hauling duties in earnest.


  1. Awesome post! I'm just starting my quest for a cargo bike. Reading your detailed post with great photos has been tremendously useful to get my mind turning over the possibilities (and challenges) of the Radish as you've configured it. Thanks and happy riding.

    - Jason

  2. Thanks, glad you enjoyed the post. Having now put several hundred miles on the Franken-Radish, I'd have to say I really like the set up I chose. The drop bars are extremely comfortable and have been a great benefit dealing with the high winds we regularly experience in Chicago. The Radish frame when mated to the FreeRadical also really does appear to be somewhat stiffer than my 1.0 version which used a cro-moly frame Specialized Stumpjumper as the donor bike.